Consumer transactions with merchants are generally made by cash, checks or credit cards. More recently, with the proliferation of mobile devices such as a cellular telephone, a Personal Digital Assistant (PDA), etc that have wireless communications functionality, consumer transactions using the mobile devices have been increased. However, such consumer transactions generally require using a credit card, a certain mobile payment service, etc. Therefore, there is an interest for a payment service that can be provided regardless of using a credit card or passing through a certain mobile payment service.